Energetic compounds, defined as the active chemical components of explosives and propellants, are necessary for a variety of purposes spanning peaceful and military applications. Common energetic compounds include the explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) as well as nitroglycerin (NG), nitroguanidine (NQ), nitrocellulose (NC), 2,4-dinitrotoluene (DNT), and various perchlorate formulations employed in missile, rocket, and gun propellants. The present description is not limited to just these compounds and may generally be applied to the wide range of nitrocompounds detailed on the “List of Explosive Materials” published in the Federal Register by the Bureau of Alcohol, Tobacco, Firearms, and Explosives.
For decades, the United States military used unlined evaporation/percolation lagoons for disposal of wastewaters from manufacturing, demilitarization, and load, assemble, and pack (LAP) operations. Many explosives have subsequently accumulated at the surfaces of lagoons, sometimes at concentrations in the percent range. These areas are a significant concern relative to long-term soil and groundwater contamination as well as for the potential for accidental detonation. Additionally, energetic materials or compounds have contaminated soils worldwide as the result of manufacturing operations, military conflict, and military training activities. Explosives such as trinitrotoluene (TNT), cyclonite (RDX), and octogen (HMX) and propellants such as nitrate esters (e.g., NG or the like) and perchlorates present the greatest concern to public health and the environment because they are manufactured and used in the greatest quantities. Unfortunately, RDX, TNT, and perchlorate are common groundwater contaminants throughout North America. In addition, many of the degradation products stemming from these compounds also pose health and environmental hazards.
Energetic compounds undergo varying degrees of chemical and biochemical transformation depending on the compounds involved and environmental factors. For example, processes that influence the environmental fate of explosive compounds may be divided into the following categories: (1) influences on transport (dissolution, volatilization, and adsorption); and (2) influences on transformation (photolysis, hydrolysis, reduction, and biological degradation).
FIG. 1 illustrates the major fate and transport pathways for energetic materials. It is clear from FIG. 1 that a complex range of degradation products are possible when these compounds are released to the environment. The typical site is contaminated with multiple energetics or energetic compounds resulting in a vast array of transformation products, which may be toxic and result in health and environmental hazards. Many of the transformation pathways shown in FIG. 1 have been exploited to develop technology for remediation of energetics based contamination in soil and groundwater.